eye movements

Eye movements 

can be classified in many ways. Perhaps the best classification scheme comes from Leigh and Zee (2006). In their book, The Neurology of Eye Movements, Leigh and Zee divide eye movements into the following functional classes:

Because eye movements vary in several important ways, many other distinctions can be made. Eye movements can be divided into conjugate (movement is the same in both eyes) and disconjugate (the eyes move a different distance or direction). Using conjugate eye movements we can look from one target to another that differs only in direction. However, targets at different distances require the eyes to change their relative orientations; looking from one target to another at a different distance requires disconjugate movements (Straumann, 2007). Vergence eye movements are disconjugate movements that move the eyes between targets that vary in distance (Busettini, Davison, Gamlin, & Squire, 2009; Gamlin, 2002; Schor & Ciuffreda, 1983). Smooth pursuit is a conjugate eye movement that facilitates tracking of a small target against a background that differs in velocity from the target (Krauzlis, 2004) for example, watching a bird in flight against the clouds in the sky. This differs from saccades, the eye movements that are used to bring the fovea to a new target or location (McDowell, Dyckman, Austin, & Clementz, 2008). These rapid eye movements are ballistic in nature and are not generally subject to modification after initiation. The remaining eye movements, vestibular stabilization or optokinetic following responses, stabilize the view during movements of the head or the visual scene (Angelaki & Squire, 2009; Kheradmand & Zee, 2011; Mustari, Ono, & Squire, 2009).

more eye movement videos at http://youtube.com/mbolding

“To construct is the essence of vision. Dispense with

construction and you dispense with vision. Everything you experience by sight is your construction.” 

Donald D. Hoffman